Beginner Quiche - cooking recipe

Ingredients

1 1/2 cups whole milk
3 eggs
2 egg yolks (save the whites for another recipe)
4 ounces shredded cheddar cheese (by weight)
4 ounces shredded swiss cheese (by weight)
4 slices american style smoked bacon, cooked and crumbled
2 small onions, thinly sliced into half-moon slices
2 tablespoons oil or 2 tablespoons butter
1 dash salt
1 teaspoon onion powder
1 dash nutmeg
pepper, to taste
2 tablespoons flour
1 par-baked pie crust (frozen is fine; I use Marie Callendar's brand)

Preparation

Preheat oven to 400 degrees. Preheat a cookie sheet or upside down cast iron pan.
Parbake pie crust by lining uncooked pie crust with parchment paper and filling with pie weights or uncooked dry beans.
Bake atop cookie sheet or cast iron pan for 10-15 minutes, or until golden brown.
While crust is baking, mix together eggs and milk until thoroughly combined.
Add onion powder, pepper and nutmeg.
Sweat onions in oil/butter until soft.
Sprinkle with salt while cooking to prevent browning.
If they get a little brown, that is okay.
Remove onions from heat and set aside.
Shred cheese, if necessary.
You should have 8 ounces total of shredded cheese. The weight is AFTER shredding.
Mix shredded cheese with flour.
Remove crust from oven.
Fill with onions, bacon, cheese in that order.
Pour egg/milk mixture over fillings until crust is full (just below the crust edge). DO NOT OVERFILL!
(If you have extra custard mix, you can cook it in small Pyrex ramekins with a bit of cheese for a crustless mini-quiche.)
Cover edges of pie crust with foil to prevent over-browning. Remove this foil for the last 10 minutes of baking.
Bake at 400 degrees for 30 minutes on the preheated cookie sheet or cast iron pan.
Allow to cool slightly before serving.
This can also be served cold for brunches or breakfast.
To reheat in the microwave, place 1 slice on a plate; cover with paper towel; warm on 70% power for 1-2 minutes.